Examination of sensory reception and integration abilities in children with and without Prader-Willi syndrome

BACKGROUND

Good postural stability control is dependent upon the complex integration of incoming sensory information (visual, somatosensory, vestibular) with neuromotor responses that are constructed in advance of a voluntary action or in response to an unexpected perturbation.

AIMS

To examine whether differences exist in how sensory inputs are used to control standing balance in children with and without Prader-Willi syndrome (PWS).

METHODS AND PROCEDURES

In this cross-sectional study, 18 children with PWS and 51 children categorized as obese but without PWS (without PWS) ages 8-11 completed the Sensory Organization Test®. This test measures the relative contributions of vision, somatosensory, and vestibular inputs to the control of standing balance. The composite equilibrium score (CES) derived from performance in all sensory conditions, in addition to equilibrium scores (EQs) and falls per condition were compared between groups.

OUTCOMES AND RESULTS

The CES was lower for children with PWS compared to children without PWS (M=53.93, SD=14.56 vs. M=66.17, SD=9.89, p = .001) while EQs declined in both groups between conditions 1 and 4 (F (1.305, 66.577) = 71.381, p < .001). No group differences in the percent of falls were evident in condition 5 but more children with PWS fell in condition 6 (χ2 (1) = 7.468, p = .006). Group differences in frequency of repeated falls also approached significance in conditions 5 (χ2 (3) = 4.630, p = .099) and 6 (χ2 (3) = 5.167, p = .076).

CONCLUSIONS AND IMPLICATIONS

Children with PWS demonstrated a lower overall level of postural control and increased sway when compared to children with obesity. Both the higher incidence and repeated nature of falls in children with PWS in conditions 5 and 6 suggest an inability to adapt to sensory conditions in which vestibular input must be prioritized. Postural control training programs in this population should include activities that improve their ability to appropriately weight sensory information in changing sensory environments, with a particular focus on the vestibular system. WHAT DOES THIS STUDY ADD?: This study shows that children with PWS demonstrate a lower level of postural stability. The results suggest that children with PWS show inability to adapt to sensory conditions that require prioritizing vestibular information to maintain postural control. This information can be used to help guide training programs in this population.

Contributing factors to postural stability in Prader-Willi syndrome

BACKGROUND

Prader-Willi Syndrome (PWS) is a rare neurodevelopmental disorder affecting multiple functional parameters. This study examined postural stability and associated gait and neuromuscular factors in young adults with PWS.

METHODS

Participants included 10 adults with PWS [7 M/3F; Body Fat % 40.61 ± 7.79]; ten normal weight (NW) adults [7 M/3F; Body Fat % 23.42 ± 7.0]; ten obese (OB) adults [7 M/3F; Body Fat % 42.40 ± 5.62]. Participants completed the Sensory Organization Test (SOT)®. Condition (C) specific and a composite equilibrium score (CES) were calculated (maximum = 100). Quadriceps strength was assessed using an isokinetic dynamometer. Three-dimensional gait analyses were completed along a 10 m walkway using a motion capture system and two force plates. A gait stability ratio (GSR) was computed from gait speed and step length (steps/m).

RESULTS

The PWS group had lower scores for C1, C3, C4 and CES compared to the NW (p < .039 for all) and lower scores for C4 and CES than the OB (p < .019 for both) groups, respectively. In C5 (eyes closed, sway-referenced support) and C6 (sway-referenced vision and support), 33.3% of participants with PWS fell during the first trial in both conditions (X2 [2] 7.436, p = .024) and (X2 [2] 7.436, p = .024) but no participant in the other groups fell. Those with PWS showed higher GSR than participants with NW (p = .005) and those with obesity (p = .045).

CONCLUSION

Individuals with PWS had more difficulty maintaining standing balance when relying on information from the somatosensory (C3), visual-vestibular (C4) and vestibular systems (C5, C6). A more stable walk was related to shorter steps, slower velocity and reduced peak quadriceps torque. Participation in multisensory activities that require appropriate prioritization of sensory system(s) input for controlling balance in altered sensory environments should be routinely included. In addition, exercises targeting muscular force and power should be included as part of exercise programming in PWS.

Effectiveness of a Parent-led Physical Activity Intervention in Youth with Obesity

PURPOSE

Prader-Willi syndrome (PWS) is a complex, rare neurobehavioral syndrome characterized by excessive fat, hypotonia, poor motor skills, and behavioral and cognitive disabilities. We tested the effectiveness of a home-based physical activity (PA) intervention led by parents in youth with obesity with and without PWS to increase moderate-to-vigorous PA (MVPA) and gross motor proficiency.

METHODS

Participants were 111 youth age 8 to 16 yr (45 with PWS and 66 without PWS, but categorized as obese). A parallel design was used with the control group (C) receiving the intervention after serving as control. Intervention participants (I) completed a PA curriculum 4 d·wk for 24 wk including warm-up exercises, strengthening exercises, and playground games 2 d·wk and interactive console games 2 d·wk guided by their parents. Pre-post outcomes (baseline to 24 wk) included MVPA (7-d accelerometry) and motor proficiency including upper limb coordination, bilateral coordination, balance, running speed and agility, and muscle strength (Bruininks-Oseretsky Test of Motor Proficiency).

RESULTS

The intervention led to no change in MVPA (I group, 39.6 vs 38.9 min·d; C group, 40.6 vs 38.3 min·d). The intervention led to improvements in body coordination (22.3%; P < 0.05), as well as strength and agility (13.7%; P < 0.05). Specifically, the I group showed increases in upper limb coordination (19.1%), bilateral coordination (27.8%), and muscle strength (12.9%; P < 0.05 for all) not observed in the C group: -0.2%, 2.5%, and -3.2%, respectively.

CONCLUSIONS

This parent-guided PA intervention did not increase PA. However, the intervention led to improvements in gross motor skill competency. Providing families with tools and support can lead to implementation of PA routines that contribute to motor skill proficiency in youth with and without PWS.

An evaluation of the implementation of a parent-led, games-based physical activity intervention: the Active Play at Home quasi-randomized trial

NCT02058342. Registered 6 February 2014 retrospectively registered.

A Characterization of Movement Skills in Obese Children With and Without Prader-Willi Syndrome

PURPOSE

The aim of this study was twofold: (a) to measure and compare motor proficiency in obese children with Prader-Willi syndrome (OB-PWS) to that in obese children without PWS (OB), and (b) to compare motor proficiency in OB-PWS and OB to normative data.

METHOD

Motor proficiency was measured using the Bruininks-Oseretsky Test of Motor Proficiency-Second Edition-Complete Form, a norm-referenced assessment of motor function. Participants were 18 OB-PWS and 44 OB (8 to 11 years of age). The scores on the 8 subtests and the total motor composite were used to compare OB-PWS and OB. Furthermore, the scores on the 4 motor-area composites were used to compare OB-PWS and OB against normative data.

RESULTS

OB-PWS scored significantly lower than OB across all 8 subtests. OB-PWS also had significantly lower motor proficiency scores on all motor-area composites when compared with the normative sample. OB-PWS most frequently (67%-83%) scored well below average on the gross motor subtests. Although not as high as on the gross motor subtests, this finding also held true for the fine motor subtests with 39% to 45% of OB-PWS scoring well below average.

CONCLUSION

Motor proficiency is very poor in OB-PWS, in particular for gross motor skills. Physical, neurological, and developmental characteristics inherent to the syndrome may explain this low performance.

Development of a Diagnostic Instrument for Evaluating Tennis Serving Performance

A learning-sequence rating form for the slice tennis serve was developed and validated. Six skill components were identified and served as the basis for evaluation. Movement characteristics for observable learning stages were also described. The videotaped serving actions of 81 tennis players of different ability were then evaluated independently by trained raters using the rating form developed. A measure of the rating form's reliability was obtained using the intraclass correlation method (R) described by Baumgartner and Jackson in 1987. Content-related evidence for validity was also obtained. Intraclass reliability coefficients ranged from .70 to .96 across the six skill components identified in the final rating form. The tennis serve rating form provides researchers and coaches a reliable and valid instrument for evaluating tennis serving performance at various stages of learning.

An evaluation of a nurse-led rehabilitation programme (the ProBalance Programme) to improve balance and reduce fall risk of community-dwelling older people: A randomised controlled trial

OBJECTIVE

This study aims to assess the effect of a nurse-led rehabilitation programme (the ProBalance Programme) on balance and fall risk of community-dwelling older people from Madeira Island, Portugal.

DESIGN

Single-blind, randomised controlled trial.

SETTING

University laboratory.

PARTICIPANTS

Community-dwelling older people, aged 65-85, with balance impairments. Participants were randomly allocated to an intervention group (IG; n=27) or a wait-list control group (CG; n=25).

INTERVENTION

A rehabilitation nursing programme included gait, balance, functional training, strengthening, flexibility, and 3D training. One trained rehabilitation nurse administered the group-based intervention over a period of 12 weeks (90min sessions, 2 days per week). A wait-list control group was instructed to maintain their usual activities during the same time period.

OUTCOME

Balance was assessed using the Fullerton Advanced Balance (FAB) scale. The time points for assessment were at zero (pre-test), 12 (post-test), and 24 weeks (follow up).

RESULTS

Changes in the mean (SD) FAB scale scores immediately following the 12-week intervention were 5.15 (2.81) for the IG and -1.45 (2.80) for the CG. At follow-up, the mean (SD) change scores were -1.88 (1.84) and 0.75 (2.99) for the IG and CG, respectively. The results of a mixed between-within subjects analysis of variance, controlling for physical activity levels at baseline, revealed a significant interaction between group and time (F (2, 42)=27.89, p<0.001, Partial Eta Squared=0.57) and a main effect for time (F (2, 43)=3.76, p=0.03, Partial Eta Squared=0.15), with both groups showing changes in the mean FAB scale scores across the three time periods. A significant main effect comparing the two groups (F (1, 43)=21.90, p<0.001, Partial Eta Squared=0.34) confirmed a clear positive effect of the intervention when compared to the control.

CONCLUSION

This study demonstrated that the rehabilitation nursing programme was effective in improving balance and reducing fall risk in a group of older people with balance impairment, immediately after the intervention. A decline in balance was observed for the IG after a period of no intervention.

CLINICAL TRIAL REGISTRATION NUMBER

ACTRN12612000301864.

Recommendations for a core outcome set for measuring standing balance in adult populations: a consensus-based approach

BACKGROUND

Standing balance is imperative for mobility and avoiding falls. Use of an excessive number of standing balance measures has limited the synthesis of balance intervention data and hampered consistent clinical practice.

OBJECTIVE

To develop recommendations for a core outcome set (COS) of standing balance measures for research and practice among adults.

METHODOLOGY

A combination of scoping reviews, literature appraisal, anonymous voting and face-to-face meetings with fourteen invited experts from a range of disciplines with international recognition in balance measurement and falls prevention. Consensus was sought over three rounds using pre-established criteria.

DATA SOURCES

The scoping review identified 56 existing standing balance measures validated in adult populations with evidence of use in the past five years, and these were considered for inclusion in the COS.

RESULTS

Fifteen measures were excluded after the first round of scoring and a further 36 after round two. Five measures were considered in round three. Two measures reached consensus for recommendation, and the expert panel recommended that at a minimum, either the Berg Balance Scale or Mini Balance Evaluation Systems Test be used when measuring standing balance in adult populations.

LIMITATIONS

Inclusion of two measures in the COS may increase the feasibility of potential uptake, but poses challenges for data synthesis. Adoption of the standing balance COS does not constitute a comprehensive balance assessment for any population, and users should include additional validated measures as appropriate.

CONCLUSIONS

The absence of a gold standard for measuring standing balance has contributed to the proliferation of outcome measures. These recommendations represent an important first step towards greater standardization in the assessment and measurement of this critical skill and will inform clinical research and practice internationally.

Rationale and design of active play @ home: a parent-led physical activity program for children with and without disability

BACKGROUND

Compared to other children, those with disability have additional challenges to being physically active. Prader-Willi Syndrome is a genetic form of childhood obesity that is characterized by hypotonia, growth hormone deficiency, behavioral, and cognitive disability. In children, the low prevalence of this syndrome (1 in 10,000 to 15,000 live births) makes group-based physical activity interventions difficult. In contrast, the home environment presents a natural venue to establish a physical activity routine for this population. This manuscript describes the design of a parent-led physical activity intervention incorporating playground and interactive console-based games to increase physical activity participation in youth with and without Prader-Willi Syndrome.

METHODS/DESIGN

The study participants will be 115 youth ages 8-15 y (45 with the syndrome and 70 without the syndrome but categorized as obese). The study will use a parallel design with the control group receiving the intervention after serving as control. Participants will be expected to complete a physical activity curriculum 4 days a week for 6 months including playground games 2 days a week and interactive console games 2 days a week. Parents will be trained at baseline and then provided with a curriculum and equipment to guide their implementation of the program. Tips related to scheduling and coping with barriers to daily program implementation will be provided. Throughout, parents will be contacted by phone once a week (weeks 1-4) and then every other week to receive support in between visits. Measurements of children and parents will be obtained at baseline, 12 weeks, and at the end (week 24) of the intervention. Children main outcomes include physical activity (accelerometry), body composition (dual x-ray absorptiometry), motor proficiency (Bruininks-Oseretsky Test of Motor Proficiency), quality of life and physical activity self-efficacy (questionnaires). Intervention compliance will be monitored using mail-in daily self-report checklists.

DISCUSSION

This parent-guided physical activity intervention aims to increase physical activity by using a curriculum that builds physical activity related self-confidence through the development and/or enhancement of motor skill competency. Ultimately, helping children develop these skills as well as joy in being physically active will translate into sustained behavior change.

TRIAL REGISTRATION

Current Controlled Trial: NCT02058342.

Rasch Analysis of the Fullerton Advanced Balance (FAB) Scale

PURPOSE

This cross-sectional study explores the psychometric properties and dimensionality of the Fullerton Advanced Balance (FAB) Scale, a multi-item balance test for higher-functioning older adults.

METHODS

Participants (n=480) were community-dwelling adults able to ambulate independently. Data gathering consisted of survey and balance performance assessment. Psychometric properties were assessed using Rasch analysis.

RESULTS

Mean age of participants was 76.4 (SD=7.1) years. Mean FAB Scale scores were 24.7/40 (SD=7.5). Analyses for scale dimensionality showed that 9 of the 10 items fit a unidimensional measure of balance. Item 10 (Reactive Postural Control) did not fit the model. The reliability of the scale to separate persons was 0.81 out of 1.00; the reliability of the scale to separate items in terms of their difficulty was 0.99 out of 1.00. Cronbach's alpha for a 10-item model was 0.805. Items of differing difficulties formed a useful ordinal hierarchy for scaling patterns of expected balance ability scoring for a normative population.

CONCLUSION

The FAB Scale appears to be a reliable and valid tool to assess balance function in higher-functioning older adults. The test was found to discriminate among participants of varying balance abilities. Further exploration of concurrent validity of Rasch-generated expected item scoring patterns should be undertaken to determine the test's diagnostic and prescriptive utility.

High-shear, jet-cooking, and alkali treatment of corn distillers' dried grains to obtain products with enhanced protein, oil and phenolic antioxidants

Distillers dried grains (DDG) have potential to be a nutritionally important source of protein, oil and phenolic antioxidants. DDG was subjected to high-shear and jet-cooking, with or without alkaline pH adjustment and autoclaving. Soluble and insoluble fractions were analyzed for protein, oil and ash. Extracts were analyzed for phenolic acids and antioxidant activity. Protein contents were significantly elevated in the insoluble fractions after treatment and the oil content was drastically increased in the insoluble fraction after high-shear and jet-cooking without pH adjustment. Alkaline pH adjustment resulted in a soluble fraction that was highest in phenolic acids, but not antioxidant activity. The highest antioxidant activity was found in the 50% ethanol extract from DDG that had been subjected to high-shear and jet-cooking. These results suggest that high-shear and jet-cooking may be useful processing treatments to increase the value of DDG by producing fractions high in protein, oil and extractable phenolic acids with high antioxidant activity. The DDG fractions and extracts described herein may be useful as food and nutraceutical ingredients, and, if used for these applications, will increase the value of DDG and ease economic burdens on ethanol producers, allowing them to compete in the bio-fuel marketplace.

Do fall predictors in middle aged and older adults predict fall status in persons 50+ with fibromyalgia? An exploratory study

We explored potential predictors of fall status in 70 community-dwelling persons > or =50 years of age with fibromyalgia (FM). Over 40% of the sample reported one or more falls in the year prior to the study. A logistic regression model using 10 variables known to predict falls in middle aged and older persons predicted 45% of the variance in fall status. Three variables offered significant independent contributions to the overall model predicting fall status: perception of postural instability, balance performance, and executive function processing speed. The results support prior work in both nonclinical and clinical populations of middle aged and older adults indicating that falls are associated with multiple risk factors. Prospective designs with larger samples are needed to (a) validate and extend these findings, and (b) identify risk factors related to fall status that are unique to persons with FM.

Predicting which older adults will or will not fall using the Fullerton Advanced Balance scale

OBJECTIVE

The purpose of this study was to determine if the Fullerton Advanced Balance (FAB) scale can predict faller status in a group of independently functioning older adults.

DESIGN

A cross-sectional design was used to establish the sensitivity and specificity of the FAB scale to predict faller status based on a retrospective self-reported fall history. For the purpose of this study, a faller was classified as an older adult with a history of 2 or more falls in the previous 12 months.

SETTING

Multipurpose senior centers in an urban community.

PARTICIPANTS

A sample of independently functioning older adults (N=192; mean age+/-SD, 77+/-6.5 y).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

FAB scale, a retrospective history of falls.

RESULTS

Binary logistic regression analysis indicated that the total FAB scale score could be used to predict faller status (as determined by a retrospective self-reported fall history). In the present sample, the probability of falling increased by 8% with each 1-point decrease in total FAB scale score. Receiver operating characteristic analysis determined that a cut-off score of 25 out of 40 on the FAB scale produced the highest sensitivity (74.6%) and specificity (52.6%) in predicting faller status. Five individual test items on the FAB scale were particularly predictive of faller status and could be combined to form a short version of the scale that may be even more predictive of faller status and require less time to administer.

CONCLUSIONS

The FAB scale is a predictive measure of faller status when used with independently functioning older adults. A practitioner can be confident in more than 7 out of 10 cases that an older adult who scores 25 or lower on the FAB scale is at high risk for falls and in need of immediate intervention.

Building an infrastructure to prevent falls in older Californians: the Fall Prevention Center of Excellence

The Fall Prevention Center of Excellence (Center), a consortium of federal, state, and private organizations, was established in 2005 to guide the implementation of a statewide initiative to prevent falls among older Californians. The process began with the convening of a representative group of recognized leaders in California's health and human services in 2003. This group engaged in a 2-day strategic planning process that culminated in the development of the California Blueprint for Fall Prevention. The overarching goal of the Blueprint is to build a statewide infrastructure for fall prevention services and programs that will serve as a model for the rest of the country. The specific goals of the Center are to establish fall prevention as a key public health priority in California; create, test, and evaluate effective and sustainable fall prevention programs; and build a comprehensive and sustainable fall prevention system in California. To accomplish these goals, the Center is currently engaged in developing and disseminating fall prevention tools and informational resources directed at the needs of both consumer and professional audiences; linking organizations involved in fall prevention while increasing awareness of fall prevention as an important public health issue; and helping communities build their capacity to effectively address falls in older adults through the delivery of integrated fall prevention services and "best practice" programs.

Preventing falls among older adults: no "one size suits all" intervention strategy

Physical activity (exercise) serves primary, secondary, and tertiary roles in the prevention of falls among older adults. In its primary role, physical activity can prevent the onset of pathology and system impairments that lead to disability and increased risk for falls. Slowing the progression of disease and system impairments is its secondary role, while its tertiary role lies in the restoration of function to a level that allows for more autonomy in the performance of essential activities of daily living. Whether used as a stand-alone strategy or a core component of a multifactorial intervention approach, exercise constitutes an effective means by which to reduce fall risk and/or fall incidence rates. At low levels of risk, many exercise choices are available to older adults. As the level of risk increases, however, more tailored and progressive exercise programs that target the physical risk factors associated with falls are more effective in lowering fall risk. Adopting a multifactorial intervention approach with exercise as an integral component may also be necessary at the highest levels of risk. Although more labor intensive, multifactorial approaches, if carefully staged, should still be considered the most effective intervention approach for older adults identified at high risk for falls.

Emerging model systems in evo-devo: horned beetles and the origins of diversity

Horned beetles and beetle horns are emerging as a model system suited to address fundamental questions in evolutionary developmental biology. Here we briefly review the biology of horned beetles and highlight the unusual opportunities they provide for evo-devo research. We then summarize recent advances in the development of new approaches and techniques that are now available to scientists interested in working with these organisms. We end by discussing ways to implement and combine these new approaches to explore new frontiers in evo-devo research previously unavailable to reseachers working outside traditional model organisms.

Development of a multidimensional balance scale for use with functionally independent older adults

OBJECTIVE

To develop and evaluate the validity and reliability of a multidimensional balance scale-the Fullerton Advanced Balance (FAB) scale-suitable for use with functionally independent older adults.

DESIGN

Psychometric evaluation of the scale's content and convergent validity, test-retest and intra- and interrater reliability, and internal rater consistency.

SETTING

Urban community.

PARTICIPANTS

Forty-six community-residing older adults (mean +/- standard deviation, 75 +/- 6.2 y), with (n = 31) and without identified balance problems (n = 15), participated in the study. Four physical therapists with expertise in the assessment and treatment of balance disorders in older adults also participated in the content validity and/or reliability phases of the study.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Spearman rank correlation coefficients for convergent validity, test-retest, intra- and interrater reliability, and homogeneity coefficient values for rater consistency.

RESULTS

Test-retest reliability for the total balance scale score was high (rho = .96). Interrater reliability for total score ranged from .94 to .97 whereas intrarater reliability coefficients ranged from .97 to 1.00. Homogeneity (H) coefficients were greater than .90 for 6 of the 10 individual test items and all 10 test items had H coefficients of greater than .75 for both rating sessions.

CONCLUSIONS

Preliminary results suggest that the FAB scale is a valid and reliable assessment tool that is suitable for use with functionally independent older adults residing in the community.

Nucleotide sequence analysis of the enteropathogenic Escherichia coli adherence factor plasmid pMAR7

The complete nucleotide sequence was determined for pMAR7, an enteropathogenic Escherichia coli (EPEC) adherence factor (EAF) plasmid that contains genes encoding a type IV attachment pilus (Bfp) and the global virulence regulator per. Prototypic EAF plasmid pMAR7 is self-transmissible, unlike the smaller EAF plasmid pB171, which has no genes encoding conjugative functions. The tra locus, a highly conserved 33-kb segment found in pMAR7, is similar to the tra (conjugation) region of the F plasmid. ISEc13 copies flanking the pMAR7 tra region could potentially mobilize or delete the tra genes. Hybridization of 134 EPEC strains showed that a complete tra region is present only in strains of the EPEC1 clonal group. This study confirms EPEC's potential for dissemination of virulence attributes by horizontal transfer of the EAF plasmid.

Functional analysis of cytoplasmic dynein heavy chain in Caenorhabditis elegans with fast-acting temperature-sensitive mutations

Cytoplasmic dynein, a minus-end-directed microtubule motor, has been implicated in many cellular and developmental processes. Identification of specific cellular processes that rely directly on dynein would be facilitated by a means to induce specific and rapid inhibition of its function. We have identified conditional variants of a Caenorhabditis elegans dynein heavy chain (DHC-1) that lose function within a minute of a modest temperature upshift. Mutant embryos generated at elevated temperature show defects in centrosome separation, pronuclear migration, rotation of the centrosome/nucleus complex, bipolar spindle assembly, anaphase chromosome segregation, and cytokinesis. Our analyses of mutant embryos generated at permissive temperature and then upshifted quickly just before events of interest indicate that DHC-1 is required specifically for rotation of the centrosome/nucleus complex, for chromosome congression to a well ordered metaphase plate, and for timely initiation of anaphase. Our results do not support the view that DHC-1 is required for anaphase B separation of spindle poles and chromosomes. A P-loop mutation identified in two independent dominant temperature-sensitive alleles of dhc-1, when engineered into the DHC1 gene of Saccharomyces cerevisiae, conferred a dominant temperature-sensitive dynein loss-of-function phenotype. This suggests that temperature-sensitive mutations can be created for time-resolved function analyses of dyneins and perhaps other P-loop proteins in a variety of model systems.

Loss of KLP-19 polar ejection force causes misorientation and missegregation of holocentric chromosomes

Holocentric chromosomes assemble kinetochores along their length instead of at a focused spot. The elongated expanse of an individual holocentric kinetochore and its potential flexibility heighten the risk of stable attachment to microtubules from both poles of the mitotic spindle (merotelic attachment), and hence aberrant segregation of chromosomes. Little is known about the mechanisms that holocentric species have evolved to avoid this type of error. Our studies of the influence of KLP-19, an essential microtubule motor, on the behavior of holocentric Caenorhabditis elegans chromosomes suggest that it has a major role in combating merotelic attachments. Depletion of KLP-19, which associates with nonkinetochore chromatin, allows aberrant poleward chromosome motion during prometaphase, misalignment of holocentric kinetochores, and multiple anaphase chromosome bridges in all mitotic divisions. Time-lapse movies of GFP-labeled mono- and bipolar spindles demonstrate that KLP-19 generates a force on relatively stiff holocentric chromosomes that pushes them away from poles. We hypothesize that this polar ejection force minimizes merotelic misattachment by maintaining a constant tension on pole-kinetochore connections throughout prometaphase, tension that compels sister kinetochores to face directly toward opposite poles.

Genome of bacteriophage P1

P1 is a bacteriophage of Escherichia coli and other enteric bacteria. It lysogenizes its hosts as a circular, low-copy-number plasmid. We have determined the complete nucleotide sequences of two strains of a P1 thermoinducible mutant, P1 c1-100. The P1 genome (93,601 bp) contains at least 117 genes, of which almost two-thirds had not been sequenced previously and 49 have no homologs in other organisms. Protein-coding genes occupy 92% of the genome and are organized in 45 operons, of which four are decisive for the choice between lysis and lysogeny. Four others ensure plasmid maintenance. The majority of the remaining 37 operons are involved in lytic development. Seventeen operons are transcribed from sigma(70) promoters directly controlled by the master phage repressor C1. Late operons are transcribed from promoters recognized by the E. coli RNA polymerase holoenzyme in the presence of the Lpa protein, the product of a C1-controlled P1 gene. Three species of P1-encoded tRNAs provide differential controls of translation, and a P1-encoded DNA methyltransferase with putative bifunctionality influences transcription, replication, and DNA packaging. The genome is particularly rich in Chi recombinogenic sites. The base content and distribution in P1 DNA indicate that replication of P1 from its plasmid origin had more impact on the base compositional asymmetries of the P1 genome than replication from the lytic origin of replication.

Sensory Organization Abilities During Upright Stance in Late-Onset Alzheimer's-Type Dementia

Postural stability was compared between individuals with mild and moderate Alzheimer's dementia and healthy older adults, using the Sensory Organization Test. Interestingly, the moderate group performed more like the healthy group than the mild group. Significant differences (p </= .008) in postural stability were found between the mild group and both the healthy and moderate Alzheimer's groups when vestibular information was critical for stability. Additional differences were found between the healthy and mild groups when vision was inaccurate. These findings suggest a decreased visual dependence in the later stages of the illness, possibly due to the visual disturbances associated with disease progression.

State of the art

Many falls and injuries related to falls can be prevented with existing knowledge and technology. But effective fall prevention will require the collaborative efforts of many organizations as well as changes in the behavior of older adults and providers, and systematic changes in organizations. Many effective interventions currently exist, but improved access, additional resources, and coordination and commitment across systems are needed. In summary, we know how to prevent falls and reduce injuries, using proven intervention strategies aimed at both low-risk and high-risk older adults. There is a wide spectrum of screening and assessment tools available and effective intervention practices. The challenge now is to put into practice throughout California the state-of-the art knowledge that has already been compiled through innovative programs and rigorous research.

A map of the interactome network of the metazoan C. elegans

To initiate studies on how protein-protein interaction (or "interactome") networks relate to multicellular functions, we have mapped a large fraction of the Caenorhabditis elegans interactome network. Starting with a subset of metazoan-specific proteins, more than 4000 interactions were identified from high-throughput, yeast two-hybrid (HT=Y2H) screens. Independent coaffinity purification assays experimentally validated the overall quality of this Y2H data set. Together with already described Y2H interactions and interologs predicted in silico, the current version of the Worm Interactome (WI5) map contains approximately 5500 interactions. Topological and biological features of this interactome network, as well as its integration with phenome and transcriptome data sets, lead to numerous biological hypotheses.

The export of coat protein from enteroaggregative Escherichia coli by a specific ATP-binding cassette transporter system

Enteroaggregative Escherichia coli (EAEC) is an emerging enteric pathogen characterized by aggregative adherence (AA) to cultured human mucosal epithelium cells. We have recently characterized a 10.2-kDa protein, called dispersin, which is exported from the bacteria and which promotes dispersal of EAEC across the intestinal mucosa. Here, we present evidence that dispersin is exported by a putative ABC transporter complex, which is encoded by a genetic locus of the EAEC virulence plasmid pAA2. We demonstrate that the locus comprises a cluster of five genes (designated aat-PABCD), including homologs of an inner-membrane permease (AatP), an ATP-binding cassette protein (AatC) and the outer membrane protein TolC (AatA). We show that, like TolC, AatA localizes to the outer membrane independently of its ABC partner. Dispersin appears to require the Aat complex for outer membrane translocation but not for secretion across the inner membrane. We also show that, like the dispersin gene, transcription of the aat cluster is dependent on AggR, a regulator of virulence genes in EAEC. We propose that the aat cluster encodes a specialized ABC transporter, which plays a role in the pathogenesis of EAEC by transporting dispersin out of the bacterial cell.

Complete genome sequence and comparative genomics of Shigella flexneri serotype 2a strain 2457T

We determined the complete genome sequence of Shigella flexneri serotype 2a strain 2457T (4,599,354 bp). Shigella species cause >1 million deaths per year from dysentery and diarrhea and have a lifestyle that is markedly different from those of closely related bacteria, including Escherichia coli. The genome exhibits the backbone and island mosaic structure of E. coli pathogens, albeit with much less horizontally transferred DNA and lacking 357 genes present in E. coli. The strain is distinctive in its large complement of insertion sequences, with several genomic rearrangements mediated by insertion sequences, 12 cryptic prophages, 372 pseudogenes, and 195 S. flexneri-specific genes. The 2457T genome was also compared with that of a recently sequenced S. flexneri 2a strain, 301. Our data are consistent with Shigella being phylogenetically indistinguishable from E. coli. The S. flexneri-specific regions contain many genes that could encode proteins with roles in virulence. Analysis of these will reveal the genetic basis for aspects of this pathogenic organism's distinctive lifestyle that have yet to be explained.

Comparative genomics of Salmonella enterica serovar Typhi strains Ty2 and CT18

We present the 4.8-Mb complete genome sequence of Salmonella enterica serovar Typhi strain Ty2, a human-specific pathogen causing typhoid fever. A comparison with the genome sequence of recently isolated S. enterica serovar Typhi strain CT18 showed that 29 of the 4,646 predicted genes in Ty2 are unique to this strain, while 84 genes are unique to CT18. Both genomes contain more than 200 pseudogenes; 9 of these genes in CT18 are intact in Ty2, while 11 intact CT18 genes are pseudogenes in Ty2. A half-genome interreplichore inversion in Ty2 relative to CT18 was confirmed. The two strains exhibit differences in prophages, insertion sequences, and island structures. While CT18 carries two plasmids, one conferring multiple drug resistance, Ty2 has no plasmids and is sensitive to antibiotics.

Extensive mosaic structure revealed by the complete genome sequence of uropathogenic Escherichia coli

We present the complete genome sequence of uropathogenic Escherichia coli, strain CFT073. A three-way genome comparison of the CFT073, enterohemorrhagic E. coli EDL933, and laboratory strain MG1655 reveals that, amazingly, only 39.2% of their combined (nonredundant) set of proteins actually are common to all three strains. The pathogen genomes are as different from each other as each pathogen is from the benign strain. The difference in disease potential between O157:H7 and CFT073 is reflected in the absence of genes for type III secretion system or phage- and plasmid-encoded toxins found in some classes of diarrheagenic E. coli. The CFT073 genome is particularly rich in genes that encode potential fimbrial adhesins, autotransporters, iron-sequestration systems, and phase-switch recombinases. Striking differences exist between the large pathogenicity islands of CFT073 and two other well-studied uropathogenic E. coli strains, J96 and 536. Comparisons indicate that extraintestinal pathogenic E. coli arose independently from multiple clonal lineages. The different E. coli pathotypes have maintained a remarkable synteny of common, vertically evolved genes, whereas many islands interrupting this common backbone have been acquired by different horizontal transfer events in each strain.